Small internal combustion engines often have a manually operated purge pump in fluid communication with a carburetor to allow fuel vapor and stale liquid fuel to be purged from the carburetor, or a prime pump to prime the carburetor with a shot of liquid fuel to facilitate starting the engine. The pumps have a manually actuated bulb and are generally attached directly to the carburetor, or located remotely from the carburetor. The purge pump is actuated to a depressed state, thereby causing liquid fuel and fuel vapor within the bulb to be directed through a downstream fuel line to a fuel tank. The purge pump is then returned to a non-depressed state, thereby drawing liquid fuel and any fuel vapor into the bulb through an upstream fuel line. The purging is generally repeated as necessary to ensure that the fuel vapor is purged from the upstream fuel line. The prime pump bulb is similarly actuated to a depressed state, however, rather than directing the flow into the fuel tank, the flow is typically directed into an air-fuel mixing passage of the carburetor to prime the carburetor.
Sometimes users mistake the purge pump for a prime pump and limit the number of actuations of the pump out of fear of “flooding” the engine. As a result, the carburetor may not be fully purged of fuel vapor prior to initiating a starting procedure for the engine, thus, making starting the engine difficult. Similarly, sometimes users mistake the prime pump for a purge pump and actuate the prime pump in excess, thereby causing the engine to be “flooded.” As a result, starting the engine is made more difficult, rather than being made easier.